Star Signs are pictures or symbols that represent a birth date from a fraction of a month to another. Star Signs would be commonly used in New Leaf in a Town Pass Card, in the section where the mayor's birthdate would be in.
There is also furniture that was distributed only for the Japanese version of Animal Crossing: New Leaf as DLC from early December 2013 - late November 2014. The items would be distributed through the months that the star signs would be enlisted in
Signs
amiibo Card Gallery
Capricorn
Aquarius
Pisces
Aries
Taurus
Gemini
Cancer
Leo
Virgo
Libra
Scorpio